EGT VS. tire size????

[RonCar]

I am New here and the first question I have been wanting to ask is, does having 35 inch tires affect EGT's? I can easily hit 1300+ and am a lil concerned with this, especially since I have exhaust(no kitty) and intake mods. I was told by a guy at a campground that my tires will cause them to be higher than normal???

 

[Hoefler]

Bigger tires are like running your truck loaded. The bigger diameter increases your final ratio. Like if you have 4. 10 going to 3. 73. It will take more power to get moving and to sustain speed. I have hit 1450 pulling 14k fifth wheel up a 6% grade. I hit 1250-1350 often pulling a 6k trailer around here for my job. I live in the Ozark mountains, lots of hills ( 6% & 8% grades all over ) and curves. No cat and aftermarket muffler.

 

[4xquadrod]

My truck spools up and runs harder faster with my 35's vs the stock tires.

 

[RonCar]

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[SRadke]

It will take more power to get moving and to sustain speed.

This is totally incorrect. It requires a certain amount of energy to accelerate a given weight to a given speed assuming all the same losses. EXACTLY the same amount of energy.



Changing your tire size changes your final drive gear ratio but it doesn't change anything in your engine. If you can hit 1300° with 35's you can also hit it with the stock 31's. What big tires does do is raise your ratios up so that you are typically working in a diffrent part of your rpm band to maintain the same speeds. Less RPM to make the same horsepower requires more torque and more torque will generally mean more heat. Hope that makes sense.



-Scott

 

[Bertram65]

This is totally incorrect. It requires a certain amount of energy to accelerate a given weight to a given speed assuming all the same losses. EXACTLY the same amount of energy.



Changing your tire size changes your final drive gear ratio but it doesn't change anything in your engine. If you can hit 1300° with 35's you can also hit it with the stock 31's. What big tires does do is raise your ratios up so that you are typically working in a diffrent part of your rpm band to maintain the same speeds. Less RPM to make the same horsepower requires more torque and more torque will generally mean more heat. Hope that makes sense.



-Scott

In theory that is correct, but if you only change to 35s and do nothing else you have the ability to put the engine under a higher load on the same piece of road. The 35s have more rolling resistance and therefore require more power to sustain the same speed in addition to changing the final drive ratio.

 

[RMachida]

In theory that is correct, but if you only change to 35s and do nothing else you have the ability to put the engine under a higher load on the same piece of road. The 35s have more rolling resistance and therefore require more power to sustain the same speed in addition to changing the final drive ratio.

There would be an increase in rolling resistence due to more rubber on the road, softer compound, more agressive tread, etc. but not an increase just due to the increase in diameter. Due to the additional mass, it will take more energy to get it rolling to the same speed.

 

[SRadke]

There would be an increase in rolling resistence due to more rubber on the road, softer compound, more agressive tread, etc. but not an increase just due to the increase in diameter. Due to the additional mass, it will take more energy to get it rolling to the same speed.

All this is correct.

 

[Bertram65]

There would be an increase in rolling resistence due to more rubber on the road, softer compound, more agressive tread, etc. but not an increase just due to the increase in diameter. Due to the additional mass, it will take more energy to get it rolling to the same speed.

All those factors are part of going to 35" tires, you would be hard pressed to find a 35" tire that was only larger in diameter and the same in all other aspects.

 

[JasonCzerak]

My truck spools up and runs harder faster with my 35's vs the stock tires.

yeah. up to about 6th gear my truck pulls harder as well but at higher speeds, things are a bit slower. I think it's an equal trade off. but not 35's. more like 33's vs's the stock 30's